Various means have been used in the prior art to give a projectile spin in order to improve the range and accuracy of a gun launched projectile. Rotating bands normally experience compressive loading conditions in the weapon due to the confinement of the rotating band between the gun tube and the projectile body. Upon exiting from the launch weapon under high spin, the rotating band is forced to suddenly experience tensile loading conditions. In prior art designs rotating band or sabot breakup was generally enhanced by putting stress risers, grooves, holes and undercuts in the rotating band wall. These prior art stress risers were successful in weakening the rotating band sufficiently to cause fragmentation outside of the gun barrel. However, a problem with these prior art devices was that the band frequently lost its structural integrity while being subjected to the compressive loading conditions in the gun tube. In the gun tube region a rotating band must remain whole in order to provide an obturating function and to impart spin to the round. In many instances structural failure of the rotating band while the projectile was being launched in the gun barrel was a cause for malfunction, loss of accuracy and loss of projectile range.